A wide variety of consumer food products, such as dairy products and the like, are typically packaged in containers which are configured to nest within one another. Such nestable containers, which typically have a circular, generally tapering configuration, facilitate high-speed packaging of such food products, in that large numbers of the containers can be compactly stored in nested relation within each other in suitable feed magazines. Attendant to product filling, the containers are denested, filled with the desired product, and usually fitted with a lid or like closure to complete filling of the container.
After product filling, it is ordinarily desirable to assemble a group of the containers into a package for subsequent storage, shipment, and eventual retail sale. One type of packaging which has proven particularly desirable is so-called shrink-wrapped packaging. This type of packaging typically employs oriented, heat-shrinkable plastic film material within which the desired group of filled containers is placed, with the film subsequently heated so that it shrinks into conformance with the assembled containers and embraces them to form an integrated package. In this manner, the containers of the package are securely held as they are handled during shipment and storage.
As will be appreciated, it is desirable that containers be assembled in a relatively closely-packaged array for shrink-wrap packaging, thereby lending to the integrity of the finished package, as well as minimizing the required quantity of heat-shrinkable plastic film. Accordingly, it is desirable to arrange nestable containers, wherein opposite ends of each container differ in dimension, in an alternately inverted array, such that each container is relatively inverted relative to the adjacent ones of the containers. In this manner, nestable containers can be arranged in a desirably compact and stable array for heat-shrink packaging.
U.S. Pat. No. 4,002,005, issued Jan. 11, 1977 to Martin Mueller et al., discloses an apparatus which facilitates packaging of nestable containers in alternately inverted arrays. The apparatus of this patent employs a transfer mechanism which is arranged to receive a stream of filled containers, and transfer the containers from one conveyor belt to another while inverting alternate ones of the containers. The containers are subsequently collated into the desired alternately inverted array for subsequent heat-shrink packaging.
Although the apparatus of the above patent provides the desired container packaging, certain disadvantages are associated with its use. Specifically, the transfer mechanisms of the apparatus are supplied with containers at spaced intervals by rotating screw indexing mechanisms. The helical flights of these indexing screws desirably present the upright containers to the transfer mechanisms at spaced intervals, but should a container be missing from between the flights of one of the screws, it must be manually replaced or else containers downstream of the transfer mechanism are not arranged in the proper alternately inverted order. Additionally, the manner in which this previous arrangement conveys containers in an alternately inverted order not only complicates inspection of the containers (such as for damaged containers, over-filled containers, or ones not properly closed), but also requires that any container which must be removed from the line be replaced with another container in the appropriately upright or inverted disposition.
The present invention improves upon previous packaging techniques, and contemplates a method and apparatus for packaging containers which facilitates high-speed operation, correct package formation, and convenient correction of any mispackaging which may occur.